/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.hadoop.hbase.util;

import java.io.DataInput;
import java.io.IOException;

public abstract class ProtoUtil {

	/**
	 * Read a variable length integer in the same format that ProtoBufs encodes.
	 * @param in the input stream to read from
	 * @return the integer
	 * @throws IOException if it is malformed or EOF.
	 */
	public static int readRawVarint32(DataInput in) throws IOException {
		byte tmp = in.readByte();
		if (tmp >= 0) {
			return tmp;
		}
		int result = tmp & 0x7f;
		if ((tmp = in.readByte()) >= 0) {
			result |= tmp << 7;
		} else {
			result |= (tmp & 0x7f) << 7;
			if ((tmp = in.readByte()) >= 0) {
				result |= tmp << 14;
			} else {
				result |= (tmp & 0x7f) << 14;
				if ((tmp = in.readByte()) >= 0) {
					result |= tmp << 21;
				} else {
					result |= (tmp & 0x7f) << 21;
					result |= (tmp = in.readByte()) << 28;
					if (tmp < 0) {
						// Discard upper 32 bits.
						for (int i = 0; i < 5; i++) {
							if (in.readByte() >= 0) {
								return result;
							}
						}
						throw new IOException("Malformed varint");
					}
				}
			}
		}
		return result;
	}

}
